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At least 127 records · Page 7Linked to original sources
PubMed1991

[The sensitization of acoustic stapedius reflex].

The acoustic stapedius reflex, which normally occurs at a hearing level of about 85 dB, can be detected at lower levels by means of sensitization. The technique is to apply reflex-eliciting tone and the facilitating tone stimulation. The high-frequency acoustic stapedius reflex can then be detected in this procedure under low-frequency facilitating. When hearing is normal, significant difference can be demonstrated between conventional and facilitated reflex threshold. There is a great amount of reflex threshold improvement with sensitization. Sensorineural hearing loss allowed small or no reflex threshold change with sensitization.

Acoustic Impedance Tests↗
PubMed1985

[Otoneurologic findings in multiple sclerosis. Stapedius reflex, vestibular evaluation, early acoustic evoked potentials].

Symptoms such as tinnitus, hearing and taste disorders and facial palsy seldom occur in multiple sclerosis. Although ENT symptoms are few, vestibular and acoustic stapedius reflex tests combined with brainstem auditory evoked potentials (BAEPs) are available, and may give very useful evidence of the existence of MS. 52 patients with definite MS, and 13 patients with probable MS were examined (classified according to the McAlpine criteria). The vestibular and acoustic stapedius reflex tests were abnormal in 51%/61% and 61%/53% respectively of both groups. The corresponding figures for BAEP were 69% and 63%. The combination of the three tests on all patients showed at least one pathological finding.

Acoustic Impedance Tests↗
PubMed1978

[Continuous stapedius reflex registration in low and high intensive levels (author's transl)].

To study the whole dynamic range of the stapedius reflex the intensity of the soundstimulus with fixed frequency is continuously changed from 70 to 115 dB. Thus we get results concerning the real reflex eleciting intensity level. the gradient caused by continuous intensity change and a possible limit of contraction. To investigate time resolution phenomenons the stimulating signal is pulsated in a second trial. We used this method of stapedius reflex registration with 48 normal ears and a group of patients with sensorineural hearing loss. The results and the diagnostic possibilities of this method are discussed.

Acoustic Stimulation↗
PubMedDate not supplied

[The use of the stapedius reflex in the fitting of hearing aids (author transl)].

The authors made experiments concerning the stapedius reflex without and with an hearing aid; there is a relation between this reflex and the discomfort threshold for the selection. The stimulus is given on a loudspeaker and the stapedius reflex permits in some cases to know the gain of the hearing aid and also the limit of discomfort. This method very useful particulary for children is objective.

Acoustic Stimulation↗
PubMed1979

A case for further quantification of the stapedius reflex.

Clinical stapedius reflex determinations presently include only threshold and decay measurements. Recent observations indicate that reflex latency, amplitude, and rise and relaxation times are sensitive to cochlear and brain stem disorders. Our investigations using a chronic animal model of an experimental acoustic tumor show that reflex amplitude, latency, and rise time are exquisitely sensitive to extrinsic pressure on the auditory nerve. Because of our observations and those of others, we suggest that further quantification of the reflex test will increase its sensitivity and reliability. Quantification can be achieved by an interface between an impedance bridge and a small computer to provide on-line averaged values for each reflex parameter.

Acoustic Impedance Tests↗
PubMed1997

Dominant hereditary conductive hearing loss due to an ossified stapedius tendon.

Familial conductive deafness is rare. This report confirms the existence of a lineage with congenital conductive hearing loss in 3 generations. The results of otologic evaluations, including pure-tone audiometry, tympanometry, acoustic reflex test, and liquid test, in 14 patients in this family were consistent with the findings of ossicular fixation in 10 patients. Tympanotomies performed in both ears of 4 patients indicated stapes ankylosis caused by ossification of the stapedius tendon. The patients gained normal hearing levels using a simple surgical procedure.

Adolescent↗
PubMed1984

Brain-stem involvement in multiple sclerosis: a comparison between brain-stem auditory evoked potentials and the acoustic stapedius reflex.

Brain-stem auditory evoked potentials (BAEPs) and the acoustic stapedius reflex (ASR) were recorded in 68 patients with definite, probable and possible multiple sclerosis (using the definitions of McAlpine). The high incidence of abnormal results, 68% and 60%, respectively, pointed to the diagnostic value of these two measures in detecting brain-stem dysfunction. Combination of the methods increased the diagnostic yield to 85%. Since in part the same brain-stem generator sites underlie BAEPs and the ASR, it was considered that a study of their correlation might serve to increase the reliability and validity of these techniques. There was 71% agreement overall between results from the two measures. Furthermore, 72% of the joint BAEP and ASR abnormalities corresponded in detection of the brain-stem lesion site. It was concluded that the combined approach may supply powerful, complementary information on brain-stem dysfunction, which may aid in establishing the diagnosis of multiple sclerosis.

Brain Stem↗
PubMed1986

Stapedius reflex in multiple sclerosis.

The stapedius reflex (StR) was studied in humans by impedance audiometry. Ipsilateral and contralateral reflexes, obtained from 48 multiple sclerosis (MS) patients and 26 controls, were analysed. MS patients showed smaller reflex amplitudes, longer onset latencies and higher contralateral reflex thresholds. Using onset latencies, 33% of all MS patients had at least two abnormal ipsi- and/or contralateral StRs. If the diagnosis was MS of the definite type, this figure was 39%. The StR is therefore a useful tool for detecting a subclinical lesion in the brainstem and can contribute to the early diagnosis of MS.

Acoustic Impedance Tests↗
PubMed1981

Ultrastructure and elemental composition of the stapedius muscle in guinea pig.

Muscules stapedius in guinea pig was investigated with regard to morphology and elemental composition. The muscle fibers are multinucleated, contain a high amount of ribosomes, and a centriole is often found adjacent to the cell nucleus. Intramitochondrial inclusion bodies occur adjacent to cristae mitochondriales. Both type I and type II fibres occur, the latter with all three subtypes. Elemental analysis from the myofibrillar area revealed unexpected low concentration of K and high concentrations of NA, P, and Ca.

Animals↗
PubMed2000

Influence of volatile and intravenous anesthetics on the threshold of the acoustically evoked stapedius reflex.

The influence of volatile and intravenous anesthetics on the threshold of the acoustically evoked stapedius reflex (SR) was studied prospectively in 45 patients undergoing elective ENT surgical procedures. After premedication with flunitrazepam the patients were randomly assigned to one of nine groups. Group I: 70% nitrous oxide (N2O) in oxygen (O2); Groups II-VII: induction of anesthesia with intravenous thiopental, followed by mask inhalation with 100% O2 and 1.13% halothane (Group II), 2.52% enflurane (Group III) or 1.73% isoflurane (Group IV); or 70% N2O in oxygen, and 0.44% halothane (Group V), 0.86% enflurane (Group VI) or 0.75% isoflurane (Group VII): Group VIII: intravenous midazolam and ketamine; and Group IX: intravenous midazolam and alfentanil. Tympanometry and ipsilateral and contralateral SR measurements were performed when the effects of the anesthetics had achieved a steady state. Flunitrazepam raised the SR threshold only slightly. Substances applied during inhalation anesthesia either markedly increased the threshold contralaterally more than ipsilaterally (thiopental, N2O), or suppressed the reflex completely (thiopental, all volatile anesthetics with or without N2O). Under intravenous anesthesia the reflex was always present. The midazolam-ketamine combination influenced the threshold bilaterally only slightly, while the midazolam-alfentanil combination led to a pronounced, contralaterally significant elevation of the threshold. Based on its minimal influence on the SR threshold, flunitrazepam is especially suitable for sedation and the midazolam-ketamine combination for anesthesia in audiological diagnostic procedures.

Acoustic Impedance Tests↗
PubMed1987

The recruitment order of stapedius motoneurons in the acoustic reflex varies with sound laterality.

In many muscles, motor units are recruited in a fixed order with increasing strength of muscular contraction. We show that for the stapedius muscle of the cat, vastly different recruitment orders can be obtained, depending on which ear is acoustically stimulated. The data support the idea that the distribution of inputs to a motoneuron pool can be inhomogeneous and a significant factor in determining recruitment order.

Animals↗
PubMed1990

Stapedius reflex thresholds in relation to tails of auditory nerve fiber frequency tuning curves.

The acoustic stapedius reflex (ASR) threshold on non-anesthetized rabbits was compared to some measures of the single auditory nerve fiber activity of rabbits. The observations were made on normal-hearing animals, with some additional data from noise-exposed individuals. The results showed that the ASR threshold was reached at a sound level above saturation of discharge rate for individual neurons at their characteristic frequency (CF) in normal animals. It was found, on the other hand, that the ASR threshold measured across frequencies from 0.25 to 12.0 kHz were at a level similar to that of the tails of the frequency tuning curves (FTCs). Cochlear lesions-induced changes in FTC tail levels were paralleled by changes in ASR threshold levels. The raise of ASR threshold was, however, somewhat larger than the raise of the tails which might be explained by the significant relative decrease in the total number of units found in the frequency region corresponding to the lesion. There was also a decrease in the high spontaneous rate (SR) compared to the low and medium SR fibers for higher frequencies. It is concluded that the FTC tails can be a major eighth-nerve correlate to ASR activation.

Acoustic Stimulation↗
PubMed1979

Infiltration of the tensor tympani and stapedius muscles in otitis media. An experimental study in the cat.

A longitudinal sequential study of otitis media was done in an experimental animal (cat) using eustachian tube obstruction. Fifty animals were used. Cellular infiltration of the tensor tympani and stapedius muscles was studied in a continuum from day 1 to 6 months after inducing otitis media. We observed that there is infiltration of the connective tissue of both muscles in otitis media, and that the cellular changes follow the same pattern as that seen in the mucoperiostium and the round window of the middle ear, although to a lesser degree. In this first report of sequential changes in middle ear muscles in otitis media, clinical implications of these findings are discussed.

Animals↗
PubMed1989

Mechanics of a single-ossicle ear: I. The extra-stapedius of the pigeon.

The motion of the conical peak of the tympanic membrane (TM) at the tip of the extra-stapedius (ES) and of the columella footplate (CFP) were measured in the pigeon using the Mössbauer technique. The dimensions of middle-ear structures were measured in some of the experimental animals. The averaged velocity response at the ES for frequencies of 0.25-2.378 kHz was that of a second order, mass and stiffness controlled, resonant system with resonant frequency of 1.2 kHz and Q3 dB of 1.2. The mean velocity amplitude at resonance was 3.7 mms-1 at 100 dB SPL, which is approximately equal to the theoretical value of 3.5 mms-1 required for maximum energy transfer from a uniform plane acoustic wavefront in air. For the frequency regions 0.125-0.25 kHz and 2.378-5.657 kHz, the mean amplitude slopes for the velocity at the ES were 2 dB oct-1 and -3 dB oct-1, respectively. Above 5.657 kHz there was considerable inter-animal variation in the ES velocity responses. The direction of motion at the ES was frequency dependent above 1 kHz. For frequencies up to 1 kHz the ratio of CFP to ES velocity was independent of frequency; the mechanical lever ratio was 2.7, which was attributed to the geometry of the middle ear. At these frequencies the total transformer ratio for the middle ear, expressing the ratio of fluid pressure at the CFP to sound pressure at the ES, was estimated to be 35 dB.

Acoustic Stimulation↗
PubMed2006

Stapedius muscle fiber characterization during postnatal development in the rat.

The stapedius muscle (SM) is reported to prevent cochlear damage by noise. Functional demands are then the ability of fast contraction with long endurance. At the end of the third postnatal week, the middle ear of the rat is completely pneumatized and according to electrophysiological data, the auditory function starts to match the adult. We investigated the developmental changes in myosin composition of SM fibres using consecutive complete SM cross-sections (taken from rats on post natal day (PND) 7, 14, 16, 21, 28, 42 and 84) which were processed by enzymehistochemistry to determine acid/alkali lability of myofibrillar adenosine triphosphatase (mATPase) and by immunohistochemistry using myosin heavy chain (MHC) antibodies (mAb). Fibres were assigned to mATPase type I, IIA, IIB, IIX or 'Miscellaneous' categories. Per mATPase category, the fibres were attributed to groups with specific MHC isoform compositions. Neonatal MHC expression could not be documented with the mAb used. However, embryonal (Emb) MHC was expressed at PND 7, very little at PND 14; at later PND fibres did not show Emb MHC. In general, the mATPase-based classification did not show large alterations after PND 21. Expression of MHC IIB, which was present in almost 50% of the fibres at PND 7 and 14, diminished to 3% at PND 84. A decrease in number of fibres expressing more than one MHC isoform was found. These results show that the SM is a precociously developing muscle compared to limb muscles and even to the diaphragm. Moreover, it is shown that the expression of the adult MHC isoform phenotype coincides with the onset of auditory function in the third postnatal week.

Adenosine Triphosphatases↗
PubMed2000

Stapedius muscle fibre composition in the rat.

The stapedius muscle (SM) is supposed to prevent cochlear damage by noise. Consequently functional demands are the ability of fast contraction with long endurance. This implies the presence of a large fraction of myosin type II fibres with an appreciable oxidative capacity. We determined the myosin composition of SM fibres using consecutive complete SM cross-sections (6 week old rats) which were processed by enzyme histochemistry (EHC) to determine acid/alkali lability of myofibrillar adenosine triphosphatase (mATPase) or by immunohistochemistry (IHC) using myosin heavy chain (MyHC) antibodies. Method accuracy was determined in co-processed extensor digitorum longus (EDL). Four hundred SM and 200 EDL fibres were assigned to mATPase type I, IIA, IIB, IIX or 'miscellaneous' ('Misc') categories. Per mATPase category the fibres were attributed to groups with specific MyHC composition. In the EDL, mATPase type I and IIB fibres expressed only MyHC I and IIB respectively, whereas about 10% of the type IIA and 40% of the type IIX fibres expressed more than one MyHC. Thus IHC detects amounts of myosin isoforms which are not detected by EHC. The mATPase IIX category criterion leaves the possibility that this category contains fibres with myosin type IIA and/or IIB in larger amounts. The criteria of the mATPase categories type I, IIA or IIB preclude assignment to these categories of fibres which also contain other myosin isoforms in larger amounts. Such fibres were classified in one of the mATPase 'Misc' categories. Thus in the EDL the capability of the EHC criteria to select 'pure' fibres in terms of myosin differs per mATPase category. None of the SM fibres were assigned to the mATPase type I or IIB categories, about 25% to the type IIA, 60% to type IIX and 15% (including most fibres which expressed MyHC I) to a 'Misc' category. All SM fibres expressed two or more MyHC isoforms, MyHC IIB occurring in all fibres and substantial amounts of MyHC IIA and/or IIX in most. These findings confirm the hypothesis that such fibres have the capacity to contract fast and have the better fatigue resistance.

Animals↗
PubMed1989

Aberrant reinervation of the stapedius muscle following facial palsy.

This case report describes the clinical course of a patient with Ramsay Hunt Syndrome. Partial recovery of the lower motor neuron facial palsy was associated with decreased hearing and a reduction of the middle ear compliance on voluntary contraction of the facial musculature. It is suggested that this is due to misdirection of regenerating nerve fibres, normally destined for facial muscles, to stapedius muscle.

Adult↗
PubMed1991

Stapedius tendon ossification: a rare cause of congenital conductive hearing loss.

Two cases are presented of bilateral conductive deafness in siblings. An initial presumptive diagnosis of otosclerosis was made in the first case, that of a nine-year-old girl with a bilateral hearing loss of 45 dB. Exploratory tympanotomy revealed normal ossicles but the stapedius 'tendon' was found to be a solid bony bar fixing the stapes. Division of the 'tendon' resulted in normal ossicular mobility and return of hearing with closure of the air-bone gap. Identical ossification was found in her other ear, and some years later in both ears of one of her brothers. Similar surgery restored hearing successfully in each case. An acquired aetiology has been proposed in one of the three previously reported cases; this report, however, suggests the congenital nature of the anomaly. No previous cases have been described occurring in siblings.

Adult↗